To quote from an XDA post:
Enabling this preference in developer options offloads task of
rendering window components like buttons, text and complex 2d graphics
calculations to GPU. This often results in much faster UI rendering
including animations. On one side you will definitely achieve better
frame rate (and hence smooth experience) throughout system, but you
may end up using more battery. On certain devices, GPU consumes more
power the CPU, hence you may observe 5-15% lower battery life with
I would recommend having this option enabled on devices with weaker
CPUs e.g. You should seldom need to enable this on dual-core 1.4ghz
Offloading UI rendering to GPU has obvious benefits so that CPU can
work on other important tasks like database IO, data manipulation,
layout calculations and responding to other user inputs.
That said, it should be up to the user to decide if he wants to trade battery life for performance. AND, I think most people would want their phones to last longer, and keep performance at an acceptable rate.